Disc brakes

ABSTRACT

Disc brake having a drum secured to the wheel to be braked and a brake disc connected by keying arrangements to the drum so as to be axially slidable relative to, but driven by, the drum. Each keying arrangement comprises interengaging projecting portions and recesses provided on the drum and disc and having coacting faces contained in axial radial planes containing the axis of rotation of the disc. At least one spring strip, provided in each keying arrangement, is mounted on the drum or disc and has a free end resiliently bearing against the disc or drum so as to maintain the disc concentric with the drum.

United States Patent Hauth [is] 3,642,101 [451 Feb. 15, 1972 [54] DISCBRAKES 21' Appl. No.: 24,137

[30] Foreign Application Priority Data Apr. 4, 1969 France ..69l0408[56] References Cited UNITED STATES PATENTS 1,933,176 10/1933 .lonsson..188/71.5 2,417,857 3/1947 Barish ..l88/73.2X

2,423,882 7/1947 Frank ..188/71.5

2,581,941 l/1952 Shinn et al. ....188/73.2

2,764,261 9/1956 Bridges ..188/73.5

FOREIGN PATENTS OR APPLICATIONS 1,177,037 12/1958 France ..188/18 APrimary Examiner-Duane A. Reger Attorney-J. Delattre-Seguy [57] ABSTRACTDisc brake having a drum secured to the wheel to be braked and a brakedisc connected by keying arrangements to the drum so as to be axiallyslidable relative to, but driven by, the drum. Each keying arrangementcomprises interengaging projectingportions and recesses provided on thedrum and disc and having coacting faces contained in axial radial planescontaining the axis of rotation of the disc. At least one spring strip,provided in each keying arrangement, is mounted on the drum or disc andhas a free end resiliently bearing against the disc or drum so as tomaintain the disc concentric with the drum.

8 Claims, 6 Drawing Figures DISC BRAKES The present invention relates todisc brakes having a floating disc and a fixed inner yoke for brakingheavy vehicles, as trucks or busses, in which the floating disc isconnected to a drum, secured to the wheel to be braked, by cooperatingprojecting portions and recesses having a keying function. When braking,the disc is gripped between shoes combined with a yoke and carrying thebrake pads, one of the pads being fixed and the other movable andcontrolled by a piston and cylinder device.

In the known brakes of this type, the aforementioned cooperatingprojecting portions and recesses (tooth or rib and notch or groove) havelateral mutually contacting faces which are parallel to one another.

This results in serious drawbacks. Indeed, when braking, the disc heatswhereas the drum substantially remains cool. The projecting portionshaving parallel faces of the disc (or drum) then become wedged in thecorresponding recesses in the drum (or disc) owing to expansion of thedisc. This prevents the disc from moving freely in a direction parallelto its axis of rotation so as to bear against the fixed brake pad. Whenthe disc rotates with the brake unapplied, there is a continuous noiseand the bearing faces are subjected to wear owing to the tapping of thefaces of the recesses against thefaces of the projecting portionsperforming the keying function.

The object of the invention is to remedy the aforementioned drawbacks. I

The invention provides a disc brake of the aforementioned typecomprising a drum secured to the wheel to be braked and a floating discconnected to rotate with the drum by a keying arrangement comprisingcooperating projecting portions and recesses, the disc being slidableaxially of the drum by the action of two brake pads which are adapted togrip the disc when braking and are located on each side of the disc,whereinthe projecting portions and recesses of the keying arrangementhave cooperating faces which are contained in radial planes containingthe axis of rotation of the disc and at least one spring strip is fixedto the drum or to the disc and bears resiliently against the disc or thedrum respectively in the region of each projecting portion and recess soas to maintain the disc resiliently centered relative to the axis ofrotation of the drum. I

With this arrangement, wedging between the projecting portions and therecesses owing to expansion of the disc and the aforementioned tappingare completely avoided and wear between the parts is much reduced.

Further features and advantages of the invention will be apparent fromthe ensuing description with reference to the accompanying drawing.

In the drawing:

FIG. 1 is a partial approximately radial sectional view of a brakeaccording to the invention;

FIG. 2 is a partial sectional view, taken along line 22 of FIG. 1, ofone arrangement for driving the disc by the drum;

FIG. 3 is a partial plan view of the arrangement shown in F IG. 2;

FIG. 4 is a diagrammatic view of a disc brake of known type, havingpairs of parallel cooperating faces for the driving of the disc by thedrum, the direction of the expansion of the disc being shown by arrows,and

H08. 5 and 6 are sectional views, similar to FIG. 2, of twomodifications according to the invention.

In the embodiment shown in FIGS. 1-3, the disc brake comprises a disc Iwhich is free to move in a direction parallel to its axis of rotationXX. The disc is driven in rotation by the drum 2, which is secured tothe wheel to be braked, through an arrangement comprising projectionportions 3 consisting of teeth equally and angularly spaced apart on theperiphery of the disc and inserted, with provision of a slightcircumferential clearance, in recesses, consisting of notches 4, in thedrum 2. The teeth and the notches have their opposed and cooperatinglateral faces 3" and 4"- contained in radial axial planes containing theaxis XX of the disc. A spring disc-centering strip 5 is secured to thedrum 2, spans each notch 4 and bears by its center portion against thecorresponding tooth 3. Preferably, the strip 5 has a width exceeding thethickness of the disc 1.

' The brake also comprises at least one yoke or stirrup comprising twohalf-yokes 6 and 7. The half-yoke 6 is directly fixed to the axle 8 ofthe wheel by a half-ring 9. Provided in the other half-yoke 7, which isintegral with the half-yoke 6, is a brake-actuating servo or piston andcylinder device 10. A brake pad 11 is secured to the half-yoke 6 andanother brake pad 12 is secured to the rod of the piston 13 of thedevice 10. The pads are parallel to the opposite faces of the disc 1.

Thedisc brake according to the invention operates in the followingmanner:

. When the brake is unapplied, the disc 1, which is driven in rotationthrough the teeth 3 and clears the brake pads 11,512 which are spacedaway from the disc, is maintained concentric with the drum2 by theaction of the strips 5.

Upon braking, the brake pad 12, carried by the half-yoke 7,

i is made to bear, by the action of the piston 13 of the device 10,

against the disc 1, which moves axially, and the disc 1 is grippedbetween the pad 12 and the fixed pad 11 anfd itlius stops rotation ofthe drum 2 and the associated wheel.

The main advantages afforded by the invention are: When braking, thedisc 1 is heated by the rubbing of the pads 11, 1'2 thereagainst whereasthe drum 2 is'heated only by radiation or heat exchange along thecontacting faces 3 and 4 of the teeth 3 and notches 4. Consequently, thedisc 1 ex-- pands much more than the drum 2. The fact that the teeth 3and the notches 4 have cooperating opposed faces 3" and 4- contained inradial axial planes containing the axis XX of the disc, allows the discto expand radially without wedging of the teeth 3 in the -notches 4.

In a disc brake of known type, shown in FIG. 4, which has parallelcooperating drive faces 3", 4", the radial expansion of the disc (seearrows) results in the two triangular zones abc of the teeth of the discexpanding also radially and these parts abc of the teeth cause the discto become wedged in the drum.

When the disc 1 rotates without applying the brake, the spring strips 5maintain the disc concentric with the drum and thereby prevent the teethfrom tapping against the notches and avoids abnormal wear of thecooperating faces of the teeth and notches.

According to a modification of the invention shown in FIG. 5, the singlespring strip 5, which was, in the embodiment just described, secured tothe drum 2 in the region of each tooth, is replaced by two spring strips5. Each of the latter is secured to the drum 2 at 13, extends as acantilever spring and resiliently bears against the tooth or the bottomof the notch in the disc.

ln the modification of the invention shown in FIG. 6, the disc 1 hasnotches 4" and the drum 2 has teeth 3". A spring strip 5" is radiallyinterposed between the tooth and the notch and secured in its centerpart at 14 to the tooth of the drum 2 and bears at its ends against thebottom of the notch in the disc.

Note that there could be used, as in the embodiment shown in FIG. 5, twospring strips which are secured to the tooth 3 (or to the bottom of thenotch 4") and bear in cantilever fashion against the bottom of the notch(or against the tooth).

Having now described my invention what I claim and desire to secure byLetters Patent is:

l. A disc brake for a wheel comprising a first element constituting arotatable drum having an axis of rotation adapted to be secured to thewheel to be braked, a second element constituted by a floatable disccoaxial with and slidable relative to the drum in a direction parallelto said axis, a plurality of circumferentially spaced keying meansconnecting the disc to the drum so that the disc rotates with the drum,each keying means comprising a projecting portion provided on one ofsaid elements and a recess provided on the other of said elements, saidprojecting portion extending radially into said recess, two brake padslocated on opposite sides of the disc and means for urging the padsagainst the disc and braking the disc, each projecting portion beingcircumferentially defined by two end faces and each recess beingcircumferentially defined by two end faces which define circumferentialclearance with said end faces of the corresponding projection, and atleast one spring strip associated with each keying means, each springstrip having one portion secured to one of said elements and havinganother portion in resiliently abutting relation to the other ofsaidelements in a region of said other element in radial alignment with saidkeying means, whereby the disc is resiliently maintained concentric withthe drum.

2. A disc brake for a wheel comprising a first element constituting arotatable drum having an axis of rotation adapted to be secured to thewheel to be braked, a second element constituted by a floatable disccoaxial with and slidable relative to the drum in a direction parallelto said axis, a plurality of circumferentially spaced keying meansconnecting the disc to the drum so that the disc rotates with the drum,each keying means comprising a projecting portion provided on one ofsaid elements and a recess provided on the other of said elements, saidprojecting portion extending radially into said recess, two brake padslocated on opposite sides of the disc and means for urging the padsagainst the disc and braking the disc, each projecting portion beingcircumferentially defined by two end faces and each recess beingcircumferentially defined by two end faces which define circumferentialclearance with said end faces of the corresponding projection, said endfaces of said projecting portions and of said recesses being containedin radial planes containing said axis, and at least one spring stripassociated with each keying means, each spring strip having one portionsecured to one of said elements and having another portion inresiliently abutting relation to the other of said elements in a regionof said other element in radial alignment with said keying means,whereby the disc is maintained concentric with the drum.

3. A disc brake for a wheel comprising a first element constituting arotatable drum having an axis of rotation adapted to be secured to thewheel to be braked, a second element constituted by a floatable disccoaxial with and slidable relative to the drum in a direction parallelto said axis, a plurality of circumferentially spaced keying meansconnecting the disc to the drum so that the disc rotates with the drum,each keying means comprising a projecting portion provided on one ofsaidelements and a recess provided on the other of said elements, saidprojecting portion extending radially into said recess, two brake padslocated on opposite sides of the disc and means for urging the padsagainst the disc and braking the disc, each projecting portion beingcircumferentially defined by two end faces and each recess beingcircumferentially defined by two end faces which define circumferentialclearance with said end faces of the corresponding projection, said endfaces of said projecting portions and of said recesses being containedin radial planes containing said axis, and at least one spring stripassociated with each keying means, each spring strip having one portionsecured to one of said elements and having another portion inresiliently abutting relation to the other of said elements in a regionof said other element in radial alignment with said keying means,whereby the disc is maintained concentric with the drum,

4. A disc brake for a wheel comprising a first element constituting arotatable drum having an axis of rotation adapted to be secured to thewheel to be braked, a second element constituted by a floatable disccoaxial with and slidable relative to the drum in a direction parallelto said axis, a plurality of circumferentially spaced keying meansconnecting the disc to the drum so that the disc rotates with the drum,each keying means comprising a projecting portion provided on one ofsaidelementsand a recess provided on the other of said elements, saidprojecting portion extending radially into said recess, two brake padslocated on opposite sides of the disc and means for urging the padsagainst the disc and braking the disc, each projecting portion beingcircumferentially defined by two end faces and each recess beingcircumferentially defined by two end faces which define circumferentialclearance with said end faces of the corresponding projection, said endfaces of said projecting portions and of said recesses being containedin radial planes containing said axis, the drum being provided with saidrecesses and the disc being provided with said projecting portions, eachspring strip having two end portions fixed to a periphery of the drumcircumferentially on each side of the corresponding recess and a centerportion in resiliently bearing relation to the corresponding projectingportion of the disc which extends into said recess.

5. A disc brake for a wheel comprising a first element constituting arotatable drum having an axis of rotation adapted to be secured to thewheel to be braked, a second element constituted by a floatable disccoaxial with and slidable relative to the drum in a direction parallelto said axis, a plurality of circumferentially spaced keying meansconnecting the disc to the drum so that the disc rotates with the drum,each keying means comprising a projecting portion provided on one ofsaid elements and a recess provided on the other of said elements, saidprojecting portion extending radially into said recess, two brake padslocated on opposite sides of the disc and means for urging the padsagainst the disc and braking the disc, each projecting portion beingcircumferentially defined by two end faces and each recess beingcircumferentially defined by two end faces which define circumferentialclearance with said end faces of the corresponding projection, said endfaces of said projecting portions and of said recesses being containedin radial planes containing said axis, the drum being provided with saidrecesses and the disc being provided with said projecting portions, twospring strips being fixed to the drum on each side of each recess, saidstrips extending in cantilever fashion from the drum and having free endportions which are in resiliently bearing relation to the correspondingprojecting portion of the disc.

6. A disc brake for a wheel comprising a fist element constituting arotatable drum having an axis of rotation adapted to be secured to thewheel to be braked, a second element constituted by a floatable disccoaxial with and slidable relative to the drum in a direction parallelto said axis, a plurality of circumferentially spaced keying meansconnecting the disc to the drum so that the disc rotates with the drum,each keying means comprising a projecting portion provided on one ofsaid elements and a recess provided on the other of said elements, saidprojecting portion extending radially into said recess, two brake padslocated on opposite sides of the disc and means for urging the padsagainst the disc and braking the disc, each projecting portion beingcircumferentially defined by two end faces and each recess beingcircumferentially defined by two end faces which define circumferentialclearance with said end faces of the corresponding projection, said endfaces of said projecting portions and of said recesses being containedin radial planes containing said axis, the disc being provided with saidrecesses and the drum being provided with said projecting portions, aspring strip being radially interposed between each projecting portionand the corresponding recess, the strip having a center portion fixed tothe projecting portion and free end portions in resiliently bearingrelation to a bottom face of the corresponding recess of the disc.

7. A disc brake for a wheel comprising a first element constituting arotatable drum having an axis of rotation adapted to be secured to thewheel to be braked, a second element constituted by a floatabledisccoaxial with and slidable relative to the drum in a direction parallelto said axis, a plurality of circumferentially spaced keying meansconnecting the disc to the drum so that the disc rotates with the drum,each keying means comprising a projecting portion provided on one pfsaidelements and a recess provided on the other of said elements, saidprojecting portion extending radially into said recess, two brake padslocated on opposite sides of the disc and means for urging the padsagainst the disc and braking the disc, each projecting portion beingcircumferentially defined by two end faces and each recess beingcircumferentially defined by two end faces which define circumferentialclearance with said end faces of the corresponding projection, said endfaces of said projecting portions and of said recesses being containedin radial planes containing said axis, the disc being provided inresiliently bearing relato a bottom face of the corresponding with saidrecesses and the drum being provided with said prorecess of the disc.J'ecting P two Spring Smp5 bemg Provlded for each P 8. A disc brake asclaimed in claim 3, wherein said strips jecting portion, each springstrip having one end portion fixed to said projecting portion and a freeend portion extending in 5 cantilever fashion from the fixed end portionof the strip and have a width exceeding the thickness of the disc.

1. A disc brake for a wheel comprising a first element constituting arotatable drum having an axis of rotation adapted to be secured to thewheel to be braked, a second element constituted by a floatable disccoaxial with and slidable relative to the drum in a direction parallelto said axis, a plurality of circumferentially spaced keying meansconnecting the disc to the drum so that the disc rotates with the drum,each keying means comprising a projecting portion provided on one ofsaid elements and a recess provided on the other of said elements, saidprojecting portion extending radially into said recess, two brake padslocated on opposite sides of the disc and means for urging the padsagainst the disc and braking the disc, each projecting portion beingcircumferentially defined by two end faces and each recess beingcircumferentially defined by two end faces which define circumferentialclearance with said end faces of the corresponding projection, and atleast one spring strip associated with each keying means, each springstrip having one portion secured to one of said elements and havinganother portion in resiliently abutting relation to the other of saidelements in a region of said other element in radial alignment with saidkeying means, whereby the disc is resiliently maintained concentric withthe drum.
 2. A disc brake for a wheel comprising a first elementconstituting a rotatable drum having an axis of rotation adapted to besecured to the wheel to be braked, a second element constituted by afloatable disc coaxial with and slidable relative to the drum in adirection parallel to said axis, a plurality of circumferentially spacedkeying means connecting the disc to the drum so that the disc rotateswith the drum, each keying means comprising a projecting portionprovided on one of said elements and a recess provided on the other ofsaid elements, said projecting portion extending radially into saidrecess, two brake pads located on opposite sides of the disc and meansfor urging the pads against the disc and braking the disc, eachprojecting portion being circumferentially defined by two end faces andeach recess being circumferentially defined by two end faces whichdefine circumferential clearance with said end faces of thecorresponding projection, said end faces of said projecting portions andof said recesses being contained in radial planes containing said axis,and at least one spring strip associated with each keying means, eachspring strip having one portion secured to one of said elements andhaving another portion in resiliently abutting relation to the other ofsaid elements in a region of said other element in radial alignment withsaid keying means, whereby the disc is maintained concentric with thedrum.
 3. A disc brake for a wheel comprising a first elementconstituting a rotatable drum having an axis of rotation adapted to besecured to the wheel to be braked, a second element constituted by afloatable disc coaxial with and slidable relative to the drum in adirection parallel to said axis, a plurality of circumferentially spacedkeying Means connecting the disc to the drum so that the disc rotateswith the drum, each keying means comprising a projecting portionprovided on one of said elements and a recess provided on the other ofsaid elements, said projecting portion extending radially into saidrecess, two brake pads located on opposite sides of the disc and meansfor urging the pads against the disc and braking the disc, eachprojecting portion being circumferentially defined by two end faces andeach recess being circumferentially defined by two end faces whichdefine circumferential clearance with said end faces of thecorresponding projection, said end faces of said projecting portions andof said recesses being contained in radial planes containing said axis,and at least one spring strip associated with each keying means, eachspring strip having one portion secured to one of said elements andhaving another portion in resiliently abutting relation to the other ofsaid elements in a region of said other element in radial alignment withsaid keying means, whereby the disc is maintained concentric with thedrum.
 4. A disc brake for a wheel comprising a first elementconstituting a rotatable drum having an axis of rotation adapted to besecured to the wheel to be braked, a second element constituted by afloatable disc coaxial with and slidable relative to the drum in adirection parallel to said axis, a plurality of circumferentially spacedkeying means connecting the disc to the drum so that the disc rotateswith the drum, each keying means comprising a projecting portionprovided on one of said elements and a recess provided on the other ofsaid elements, said projecting portion extending radially into saidrecess, two brake pads located on opposite sides of the disc and meansfor urging the pads against the disc and braking the disc, eachprojecting portion being circumferentially defined by two end faces andeach recess being circumferentially defined by two end faces whichdefine circumferential clearance with said end faces of thecorresponding projection, said end faces of said projecting portions andof said recesses being contained in radial planes containing said axis,the drum being provided with said recesses and the disc being providedwith said projecting portions, each spring strip having two end portionsfixed to a periphery of the drum circumferentially on each side of thecorresponding recess and a center portion in resiliently bearingrelation to the corresponding projecting portion of the disc whichextends into said recess.
 5. A disc brake for a wheel comprising a firstelement constituting a rotatable drum having an axis of rotation adaptedto be secured to the wheel to be braked, a second element constituted bya floatable disc coaxial with and slidable relative to the drum in adirection parallel to said axis, a plurality of circumferentially spacedkeying means connecting the disc to the drum so that the disc rotateswith the drum, each keying means comprising a projecting portionprovided on one of said elements and a recess provided on the other ofsaid elements, said projecting portion extending radially into saidrecess, two brake pads located on opposite sides of the disc and meansfor urging the pads against the disc and braking the disc, eachprojecting portion being circumferentially defined by two end faces andeach recess being circumferentially defined by two end faces whichdefine circumferential clearance with said end faces of thecorresponding projection, said end faces of said projecting portions andof said recesses being contained in radial planes containing said axis,the drum being provided with said recesses and the disc being providedwith said projecting portions, two spring strips being fixed to the drumon each side of each recess, said strips extending in cantilever fashionfrom the drum and having free end portions which are in resilientlybearing relation to the corresponding projecting portion of the disc. 6.A disc brake for a wheel coMprising a fist element constituting arotatable drum having an axis of rotation adapted to be secured to thewheel to be braked, a second element constituted by a floatable disccoaxial with and slidable relative to the drum in a direction parallelto said axis, a plurality of circumferentially spaced keying meansconnecting the disc to the drum so that the disc rotates with the drum,each keying means comprising a projecting portion provided on one ofsaid elements and a recess provided on the other of said elements, saidprojecting portion extending radially into said recess, two brake padslocated on opposite sides of the disc and means for urging the padsagainst the disc and braking the disc, each projecting portion beingcircumferentially defined by two end faces and each recess beingcircumferentially defined by two end faces which define circumferentialclearance with said end faces of the corresponding projection, said endfaces of said projecting portions and of said recesses being containedin radial planes containing said axis, the disc being provided with saidrecesses and the drum being provided with said projecting portions, aspring strip being radially interposed between each projecting portionand the corresponding recess, the strip having a center portion fixed tothe projecting portion and free end portions in resiliently bearingrelation to a bottom face of the corresponding recess of the disc.
 7. Adisc brake for a wheel comprising a first element constituting arotatable drum having an axis of rotation adapted to be secured to thewheel to be braked, a second element constituted by a floatable disccoaxial with and slidable relative to the drum in a direction parallelto said axis, a plurality of circumferentially spaced keying meansconnecting the disc to the drum so that the disc rotates with the drum,each keying means comprising a projecting portion provided on one ofsaid elements and a recess provided on the other of said elements, saidprojecting portion extending radially into said recess, two brake padslocated on opposite sides of the disc and means for urging the padsagainst the disc and braking the disc, each projecting portion beingcircumferentially defined by two end faces and each recess beingcircumferentially defined by two end faces which define circumferentialclearance with said end faces of the corresponding projection, said endfaces of said projecting portions and of said recesses being containedin radial planes containing said axis, the disc being provided with saidrecesses and the drum being provided with said projecting portions, twospring strips being provided for each projecting portion, each springstrip having one end portion fixed to said projecting portion and a freeend portion extending in cantilever fashion from the fixed end portionof the strip and in resiliently bearing relato a bottom face of thecorresponding recess of the disc.
 8. A disc brake as claimed in claim 3,wherein said strips have a width exceeding the thickness of the disc.